Solar water heating system with double-row vacuum tubes

ABSTRACT

The invention provides a solar water heating apparatus with double-row vacuum tubes coupled to a water tank made of stainless steel or enamel. Each of the vacuum tubes is made of an exterior tube and an interior tube separated by a vacuum. The exterior tube is transparent. The interior tube is covered with a layer of light-absorption material. When sunlight shines on the vacuum tube, the water in the tank and the water in the interior tube circulate by convection.

FIELD OF THE INVENTION

This invention generally relates to the technology of using solar thermal energy. In particular, this invention relates to a solar water heating system with double-row vacuum tubes coupled to a water tank made of stainless steel or enamel.

BACKGROUND OF THE INVENTION

Solar water heaters have been widely used for years in many countries. Most of solar water heaters in the market use vacuum tubes for collecting heat energy from sun lights. The vacuum tubes are arranged in an array of a single row and multiple columns. The thermal efficiency of this type of implementation is limited due to the small lighting surface.

What is desired is a solution to enlarge the effective lighting surfaces without changing the overall length and width of the apparatus.

SUMMARY OF THE INVENTION

The present invention provides a solution to enlarge the effective lighting surfaces without changing the overall length and width of the equipment.

The apparatus according to the preferred embodiment includes a support frame, an array of straight vacuum tubes which are arranged in two layers, and a cylindrical double-layer water tank.

The support frame provides a flat surface with an upper end and a lower end. The upper end and the lower end are paralleled to each other. Since the upper end is higher than the lower end, the flat surface has a slope, i.e. there is an angle between the flat surface and the horizontal line.

The straight double-layer vacuum pipes are paralleled to each other and are fixed along the flat surface from the flat surface's lower end to the flat surface's upper end.

The cylindrical double-layer water tank is mechanically coupled to the flat surface's upper end. The water tank is a dual layer container. Its exterior layer is made of colored steel or aluminum and its interior layer is made of stainless steel or enamel. The water tank's longitudinal direction is vertical to the vacuum pipes and is paralleled to the flat surface's upper end. The water tank has an inlet which is hydraulically coupled to a water supply source. It also has an outlet for outputting heated water from the water tank to the user.

Each vacuum pipe's lower end is a dead end and each pipe's upper end is hydraulically coupled to the water tank's lower portion. The water in the tank and the water in the vacuum tubes can be circulated by convection.

Each vacuum pipe is at an angle of approximately 45 degree with the water tank's vertical central cross-sectional surface. In other words, the coupling point of a vacuum tube with the water tank is approximately at the 7:30 o'clock position of the water tank's vertical cross-section.

The array of straight vacuum pipes has a first layer and a second layer. The second layer is fixed below the first layer. Each vacuum pipe in the second layer, except the two pipes at the edges, faces to a gap between two adjacent pipes in the first layer.

Preferably, the flat surface's slope can be adjusted by changing the relational position of the supportive parts of the frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a solar heating system according to the present invention.

FIG. 2 is a top view of the solar heating system according to the present invention;

FIG. 3 is a schematic D-D cross-sectional view of the tube arrangement in FIG. 2; and

FIG. 4 is a schematic sectional view of an alternative tube arrangement.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention may be embodied in many different shapes, forms, designs or configurations, for the purpose of promoting an understanding of the principles of the invention, reference will be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further implementations of the principle, the essence or the spirit of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.

FIG. 1 illustrates a side view of the solar heating system according to the present invention. FIG. 2 illustrates a top view of the heating system according to FIG. 1.

The heating system according to FIG. 1 and FIG. 2 includes a thermos 1, a frame 2, a two-layer array of vacuum tubes 3, and a supportive accessory 4 to support the lower ends of the vacuum tubes. The thermos 1 is a cylindrical water tank having an inlet connected to a water supply and an outlet for outputting the heated water. The inlet and the outlet are not shown in FIG. 1 and FIG. 2. The vacuum tubes are made of glass or other transparent materials. Each tube has an inner layer and an exterior layer. The space between the inner layer and the exterior layer is entirely devoid of air. The inner layer is covered with light abortion materials. The sunlight penetrates the vacuum and heats the inner layer which then heats the water inside the pipe. The water with a higher temperature moves upward and enters the thermos 1, and the gravity makes the water with a lower temperature moves downward along the pipe. In such a manner, the temperature of the water in the thermos 1 increases gradually. After a while, the water in the thermos 1 can be used. The inlet can be coupled to a sensor and an electronic automatic switch. When the water in the tank is lower than a certain level, the switch is on and more cold water is input into the tank from the water supply. When the water in the tank approaches to a certain level, the switch is off.

The thermos 1 is a dual layer cylindrical container. The exterior layer is made of colored steel or aluminum and the interior layer is made of stainless steel or enamel. The thermos 1 is fixed at the upper end of the frame 2. The longitudinal direction of thermos 1 is vertical to the straight vacuum pipes 3.

The frame 2 includes a hypotenuse surface 11, two or more vertical paralleling legs, and various connecting arms to connect the legs and the hypotenuse surface. The slope of the vacuum pipes, i.e. the angle a between the hypotenuse surface 11 and the horizontal surface 12 can be adjusted by changing the relative positions of the connecting arms and the legs using the conventional technology.

The vacuum tubes 3 have identical length and diameter. They are paralleled to each other along the direction of the hypotenuse surface 11 and are arranged into a two-layer array. Each pipe is hydraulically coupled to the lower portion 21 of the thermos 1. In other words, the water in the vacuum pipe can flow into the tank and the water in the tank can flow into the vacuum pipe. In the preferred embodiment, each pipe is at an angle β vertical to a central cross-sectional surface 13. Angle β is approximately 45 degrees. More specifically, the connecting point of a vacuum with the water tank is approximately at the 7:30 O'clock position of the water tank's vertical cross-section.

Referring to FIG. 3 and FIG. 4, in each layer, there is a gap 31 between two adjacent tubes. The gap 31 is the same as or wider than the tube's diameter. The tubes in the bottom layer are positioned under the gaps of the top layer. The distance 32 between the lower surface of the top layer and the upper surface of the bottom layer is larger than zero. This configuration provides the maximized light absorption surfaces from morning to the evening.

The vacuum tube according to the present invention is made of an exterior tube and an interior tube separated by a vacuum. The exterior tube is transparent. The interior tube is covered with a layer of light-absorption material. The sunlight penetrates the vacuum and shines on the light-absorption material which transfers the light energy into heat energy. The heat energy increases the temperature of the water inside of the inner tube. Since the density of warm water is lower than the density of cold water, the warm water flows upward and the cold water flows downward and thus the water in the tube and the tank circulates by convection. As a result, the temperature of the water in the tank is gradually increased with the sun shining. The function of the vacuum is to allow the sunlight in and prevent heat loss.

While one or more embodiments of the present invention have been illustrated above, the skilled artisan will appreciate that modifications and adoptions to those embodiments may be made without departing from the scope and spirit of the present invention. 

1. An apparatus for heating water using solar energy, comprising: a support frame proving a hypotenuse flat surface with an upper end and a lower end, said upper end and said lower end being paralleled to each other; an array of straight vacuum pipes, said pipes being paralleled to each other and being fixed along said flat surface from said flat surface's lower end to said flat surface's upper end; a cylindrical water tank being coupled to said flat surface's upper end, said water tank's longitudinal direction being vertical to said vacuum pipes and being paralleled to said flat surface's upper end; wherein said water tank has an inlet which is hydraulically coupled to a water supply source and an outlet for outputting heated water from said water tank; wherein each vacuum pipe's lower end is a dead end and each pipe's upper end is hydraulically coupled to said water tank's lower portion; wherein each pipe is at an angle of approximately 45 degree with said water tank's vertical central cross-sectional surface; and wherein said array of vacuum pipes has a first layer and a second layer, said second layer being fixed below said first layer, and each pipe in said second layer facing to a gap between two adjacent pipes in said first layer.
 2. The apparatus of claim 1, wherein said gap is not less than each pipe's diameter.
 3. The apparatus of claim 1, wherein a distance between a lower surface of said first layer and an upper surface of said second layer is larger than zero.
 4. The apparatus of claim 1, wherein said flat surface's slope is adjustable.
 5. The apparatus of claim 1, wherein said water tank is a dual layer container, its exterior layer being made of colored steel or aluminum and its interior layer being made of stainless steel or enamel.
 6. The apparatus of claim 1, wherein each of said vacuum tubes comprises an exterior tube and an interior tube which are separated by a vacuum, wherein said exterior tube is transparent and said interior tube is covered with a layer of light-absorption material.
 7. The apparatus of claim 1, wherein said inlet is coupled to a sensor and an electronic switch. 